1. Field of the Invention
This invention relates generally to dual-inline memory modules (DIMMs), and more particularly to the physical characteristics of such DIMMs.
2. Description of the Related Art
Conventional computer memory systems provide random access memory by means of dual-inline memory modules (DIMMs), which are plugged into respective slots on the computer's motherboard. A number of individual RAM chips—typically dynamic RAM (DRAM)—reside on each DIMM.
The physical and electrical characteristics of a given DIMM module are governed by various industry standards documents, typically those promulgated by the Joint Electron Device Engineering Council (JEDEC). For example, a set of JEDEC standards governing the characteristics of a DDR3 SDRAM DIMM specifies that the DIMM module have a height that is no greater than approximately 30 mm; such a DIMM can accommodate up to two rows of DRAMs.
This height limitation imposes a limit on the DIMM's memory capacity. One way of overcoming this limitation is to use ‘stacked’ DRAM chips, each of which consists of two or more DRAM circuits within a single DRAM package, instead of conventional non-stacked (planar) DRAMs. However, stacked DRAMs tend to be both more expensive and less reliable than conventional DRAMs.